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Wang L, Wang YY, Chen ZL, Li YH. Enzymatic characterization and thermostability improvement of an acidophilic endoxylanase PphXyn11 from Paenibacillus physcomitrellae XB. Protein Expr Purif 2024; 219:106482. [PMID: 38583789 DOI: 10.1016/j.pep.2024.106482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 03/24/2024] [Accepted: 04/04/2024] [Indexed: 04/09/2024]
Abstract
GH11 enzyme is known to be specific and efficient for the hydrolysis of xylan. It has been isolated from many microorganisms, and its enzymatic characteristics and thermostability vary between species. In this study, a GH11 enzyme PphXyn11 from a novel xylan-degrading strain of Paenibacillus physcomitrellae XB was characterized, and five mutants were constructed to try to improve the enzyme's thermostability. The results showed that PphXyn11 was an acidophilic endo-β-1,4-xylanase with the optimal reaction pH of 3.0-4.0, and it could deconstruct different kinds of xylan substrates efficiently, such as beechwood xylan, wheat arabinoxylan and xylo-oligosaccharides, to produce xylobiose and xylotriose as the main products at the optimal reaction temperature of 40 °C. Improvement of the thermal stability of PphXyn11 using site-directed mutagenesis revealed that three mutants, W33C/N47C, S127C/N174C and S49E, designed by adding the disulfide bonds at the N-terminal, C-terminal and increasing the charged residues on the surface of PphXyn11 respectively, could increase the enzymatic activity and thermal stablility significantly and make the optimal reaction temperature reach 50 °C. Molecular dynamics simulations as well as computed the numbers of salt bridges and hydrogen bonds indicated that the protein structures of these three mutants were more stable than the wild type, which provided theoretical support for their improved thermal stability. Certainly, further research is necessary to improve the enzymatic characteristics of PphXyn11 to achieve the bioconversion of hemicellulosic biomass on an applicable scale.
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Affiliation(s)
- Le Wang
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Yan Yan Wang
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Zhi Ling Chen
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Yan Hong Li
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
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Wang T, Lin M, Yan Y, Jiang S, Dai Q, Zhou Z, Wang J. Identification of a novel glycoside hydrolase family 8 xylanase from Deinococcus geothermalis and its application at low temperatures. Arch Microbiol 2024; 206:307. [PMID: 38884653 DOI: 10.1007/s00203-024-04055-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 06/12/2024] [Accepted: 06/15/2024] [Indexed: 06/18/2024]
Abstract
Xylanase is the most important hydrolase in the xylan hydrolase system, the main function of which is β-1,4-endo-xylanase, which randomly cleaves xylans to xylo-oligosaccharides and xylose. Xylanase has wide ranging of applications, but there remains little research on the cold-adapted enzymes required in some low-temperature industries. Glycoside hydrolase family 8 (GH8) xylanases have been reported to have cold-adapted enzyme activity. In this study, the xylanase gene dgeoxyn was excavated from Deinococcus geothermalis through sequence alignment. The recombinant xylanase DgeoXyn encodes 403 amino acids with a theoretical molecular weight of 45.39 kDa. Structural analysis showed that DgeoXyn has a (α/α)6-barrel fold structure typical of GH8 xylanase. At the same time, it has strict substrate specificity, is only active against xylan, and its hydrolysis products include xylobiose, xylotrinose, xytetranose, xylenanose, and a small amount of xylose. DgeoXyn is most active at 70 ℃ and pH 6.0. It is very stable at 10, 20, and 30 ℃, retaining more than 80% of its maximum enzyme activity. The enzyme activity of DgeoXyn increased by 10% after the addition of Mn2+ and decreased by 80% after the addition of Cu2+. The Km and Vmax of dgeox were 42 mg/ml and 20,000 U/mg, respectively, at a temperature of 70 ℃ and pH of 6.0 using 10 mg/ml beechwood xylan as the substrate. This research on DgeoXyn will provide a theoretical basis for the development and application of low-temperature xylanase.
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Affiliation(s)
- Tingting Wang
- College of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621000, China
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
- Key Laboratory of Agricultural Microbiome (MARA), Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Min Lin
- College of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621000, China
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
- Key Laboratory of Agricultural Microbiome (MARA), Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Yongliang Yan
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
- Key Laboratory of Agricultural Microbiome (MARA), Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Shijie Jiang
- College of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621000, China
| | - Qilin Dai
- College of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621000, China
| | - Zhengfu Zhou
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
- Key Laboratory of Agricultural Microbiome (MARA), Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Jin Wang
- College of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621000, China
- National Key Laboratory of Agricultural Microbiology, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
- Key Laboratory of Agricultural Microbiome (MARA), Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
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3
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Xu SY, Zhou L, Xu Y, Hong HY, Dai C, Wang YJ, Zheng YG. Recent advances in structure-based enzyme engineering for functional reconstruction. Biotechnol Bioeng 2023; 120:3427-3445. [PMID: 37638646 DOI: 10.1002/bit.28540] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/27/2023] [Accepted: 08/15/2023] [Indexed: 08/29/2023]
Abstract
Structural information can help engineer enzymes. Usually, specific amino acids in particular regions are targeted for functional reconstruction to enhance the catalytic performance, including activity, stereoselectivity, and thermostability. Appropriate selection of target sites is the key to structure-based design, which requires elucidation of the structure-function relationships. Here, we summarize the mutations of residues in different specific regions, including active center, access tunnels, and flexible loops, on fine-tuning the catalytic performance of enzymes, and discuss the effects of altering the local structural environment on the functions. In addition, we keep up with the recent progress of structure-based approaches for enzyme engineering, aiming to provide some guidance on how to take advantage of the structural information.
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Affiliation(s)
- Shen-Yuan Xu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | - Lei Zhou
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | - Ying Xu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | - Han-Yue Hong
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | - Chen Dai
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | - Ya-Jun Wang
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
| | - Yu-Guo Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- Engineering Research Center of Bioconversion and Biopurification of the Ministry of Education, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, People's Republic of China
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Sharma N, Agarwal A, Bijoy A, Pandit S, Sharma RK. Lignocellulolytic extremozymes and their biotechnological applications. Extremophiles 2023; 28:2. [PMID: 37950773 DOI: 10.1007/s00792-023-01314-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 09/26/2023] [Indexed: 11/13/2023]
Abstract
Lignocellulolytic enzymes are used in different industrial and environmental processes. The rigorous operating circumstances of these industries, however, might prevent these enzymes from performing as intended. On the other side, extremozymes are enzymes produced by extremophiles that can function in extremely acidic or basic; hot or cold; under high or low salinity conditions. These severe conditions might denature the normal enzymes that are produced by mesophilic microorganisms. The increased stability of these enzymes has been contributed to a number of conformational modifications in their structures. These modifications may result from a few amino acid substitutions, an improved hydrophobic core, the existence of extra ion pairs and salt bridges, an increase in compactness, or an increase in positively charged amino acids. These enzymes are the best option for industrial and bioremediation activities that must be carried out under difficult conditions due to their improved stability. The review, therefore, discusses lignocellulolytic extremozymes, their structure and mechanisms along with industrial and biotechnological applications.
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Affiliation(s)
- Nikita Sharma
- Department of Biosciences, Manipal University Jaipur, Jaipur, 303007, Rajasthan, India
| | - Aditi Agarwal
- Department of Biosciences, Manipal University Jaipur, Jaipur, 303007, Rajasthan, India
| | - Ananya Bijoy
- Department of Biosciences, Manipal University Jaipur, Jaipur, 303007, Rajasthan, India
| | - Sunidhi Pandit
- Department of Biosciences, Manipal University Jaipur, Jaipur, 303007, Rajasthan, India
| | - Rakesh Kumar Sharma
- Department of Life Sciences, Chhatrapati Shahu Ji Maharaj University, Kanpur, India.
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Wu Q, Zhang C, Dong W, Lu H, Yang Y, Li W, Xu Y, Li X. Simultaneously Enhanced Thermostability and Catalytic Activity of Xylanase from Streptomyces rameus L2001 by Rigidifying Flexible Regions in Loop Regions of the N-Terminus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:12785-12796. [PMID: 37590476 DOI: 10.1021/acs.jafc.3c03871] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
The GH11 xylanase XynA from Streptomyces rameus L2001 has favorable hydrolytic properties. However, its poor thermal stability hinders its widespread application in industry. In this study, mutants Mut1 and Mut2 were constructed by rationally combining the mutations 11YHDGYF16, 23AP24/23SP24, and 32GP33. The residual enzyme activity of these combinational mutants was more than 85% when incubated at 80 and 90 °C for 12 h, and thus are the most thermotolerant xylanases known to date. The reduced flexibility of the N-terminus, increased overall rigidity, as well as the surface net charge of Mut1 and Mut2 may be partially responsible for the improved thermal stability. In addition, the specific activity and catalytic efficiency of Mut1 and Mut2 were improved compared with those of wild-type XynA. The broader catalytic cleft and enhanced flexibility of the "thumb" of Mut1 and Mut2 may be partially responsible for the improved specific activity and catalytic efficiency.
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Affiliation(s)
- Qiuhua Wu
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Chengnan Zhang
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Wenqi Dong
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Hongyun Lu
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Yue Yang
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Weiwei Li
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Youqiang Xu
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
| | - Xiuting Li
- Ministry of Education, Key Laboratory of Geriatric Nutrition and Health (Beijing Technology and Business University), Beijing 100048, China
- China General Chamber of Commerce, Key Laboratory of Brewing Microbiome and Enzymatic Molecular Engineering, Beijing 100048, China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
- Beijing Association for Science and Technology-Food Nutrition and Safety Professional Think Tank Base, Beijing 100048, China
- School of Food and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China
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Li Y, Song W, Han X, Wang Y, Rao S, Zhang Q, Zhou J, Li J, Liu S, Du G. Recent progress in key lignocellulosic enzymes: Enzyme discovery, molecular modifications, production, and enzymatic biomass saccharification. BIORESOURCE TECHNOLOGY 2022; 363:127986. [PMID: 36126851 DOI: 10.1016/j.biortech.2022.127986] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 05/15/2023]
Abstract
Lignocellulose, the most prevalent biomass on earth, can be enzymatically converted into carbohydrates for bioethanol production and other uses. Among lignocellulosic enzymes, endoglucanase, xylanase, and laccase are the key enzymes, owing to their ability to disrupt the main structure of lignocellulose. Recently, new discovery methods have been established to obtain key lignocellulosic enzymes with excellent enzymatic properties. Molecular modification of enzymes to modulate their thermostability, catalytic activity, and substrate specificity has been performed with protein engineering technology. In addition, the enzyme expression has been effectively improved through expression element screening and host modification, as well as fermentation optimization. Immobilization of enzymes, use of surfactants, synergistic degradation, and optimization of reaction conditions have addressed the inefficiency of enzymatic saccharification. In this review, recent advances in key lignocellulosic enzymes are summarized, along with future prospects for the development of super-engineered strains and integrative technologies for enzymatic biomass saccharification.
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Affiliation(s)
- Yangyang Li
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Weiyan Song
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Xuyue Han
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Yachan Wang
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Shengqi Rao
- College of Food Science and Engineering, Yangzhou University, Yangzhou 214122, China
| | - Quan Zhang
- Dalian Research Institute of Petroleum and Petrochemicals, SINOPEC, Dalian 116000, China
| | - Jingwen Zhou
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jianghua Li
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Song Liu
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China.
| | - Guocheng Du
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
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Wang Y, Wang J, Zhang Z, Yang J, Turunen O, Xiong H. High-temperature behavior of hyperthermostable Thermotoga maritima xylanase XYN10B after designed and evolved mutations. Appl Microbiol Biotechnol 2022; 106:2017-2027. [PMID: 35171339 DOI: 10.1007/s00253-022-11823-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/29/2022] [Accepted: 02/05/2022] [Indexed: 11/24/2022]
Abstract
A hyperthermostable xylanase XYN10B from Thermotoga maritima (PDB code 1VBR, GenBank accession number KR078269) was subjected to site-directed and error-prone PCR mutagenesis. From the selected five mutants, the two site-directed mutants (F806H and F806V) showed a 3.3-3.5-fold improved enzyme half-life at 100 °C. The mutant XYNA generated by error-prone PCR showed slightly improved stability at 100 °C and a lower Km. In XYNB and XYNC, the additional mutations over XYNA decreased the thermostability and temperature optimum, while elevating the Km. In XYNC, two large side-chains were introduced into the protein's interior. Micro-differential scanning calorimetry (DSC) showed that the melting temperature (Tm) dropped in XYNB and XYNC from 104.9 °C to 93.7 °C and 78.6 °C, respectively. The detrimental mutations showed that extremely thermostable enzymes can tolerate quite radical mutations in the protein's interior and still retain high thermostability. The analysis of mutations (F806H and F806V) in a hydrophobic area lining the substrate-binding region indicated that active site hydrophobicity is important for high activity at extreme temperatures. Although polar His at 806 provided higher stability, the hydrophobic Phe at 806 provided higher activity than His. This study generates an understanding of how extreme thermostability and high activity are formed in GH10 xylanases. KEY POINTS: • Characterization and molecular dynamics simulations of TmXYN10B and its mutants • Explanation of structural stability of GH10 xylanase.
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Affiliation(s)
- Yawei Wang
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430048, China
| | - Jing Wang
- College of Life Science, South-central University for Nationalities, Wuhan, 430074, China
| | - Zhongqiang Zhang
- College of Life Science, South-central University for Nationalities, Wuhan, 430074, China
| | - Jiangke Yang
- College of Life Science and Technology, Wuhan Polytechnic University, Wuhan, 430048, China
| | - Ossi Turunen
- School of Forest Sciences, University of Eastern Finland, FI-80101, Joensuu, Finland.
| | - Hairong Xiong
- College of Life Science, South-central University for Nationalities, Wuhan, 430074, China.
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